The present invention relates to a motor operated butterfly valve arrangement for controlling the opening state of at least one pipe, comprising at least one valve element movably arranged within the pipe, a motor, and a coupling mechanism between the motor, and the valve element in order to vary the orientation of the valve element in relation to the pipe between different opening states with differing orientations of the valve element. At least one of the opening states is defined by mechanical contact between the valve element and a stopper of the pipe. The invention relates to a motor operated butterfly valve having a valve element arranged within a pipe. The valve element has an orientation thereof varied through operation of a motor to control an opening state of the pipe.
Motor operated butterfly valves can be used for controlling the opening/closing/switching, etc. of hot water piping in an automobile air-conditioner, for example. Generally the orientation of a least one disk-shaped valve element provided inside a pipe is varied by the driving force of a motor to control the opening state of the pipe.
In practice, motor operated butterfly valves are controlled such that the motor simply is stopped at, e.g. an extreme stop position of the valve element. This can be the fully closed position at which the pipe is fully closed. A satisfactory fully closed state often cannot be achieved due to unavoidable errors attributable to dimensional accuracy and mounting accuracy of the components. If the extreme stop position is the fully closed position, then water may still leak through. If the extreme stop position is the fully opened position, said valve element may cause an undesirable flow throttling effect.
In practice it is known to overcome said problems by locking the motor in a state when the valve element remains loaded in its closing direction even at the fully closed position in order to intentionally press said valve element into its fully closed position. This is however, not desirable in view to the durability of the motor.
There are butterfly valve arrangements comprising a plurality of valve elements collectively controlled in parallel with each other. Even if said valve elements are driven to carry out exactly the same opening and closing motions, the respectively achievable opening or closing states may slightly differ among the valve elements due to errors attributable to dimensional accuracy, mounting accuracy, differing slacks in the driving mechanism, etc. Accordingly, in such cases for safety sake for each valve element an own motor is to be provided. This is uneconomical since the cost of parts are high and the mounting space is excessively large.
It is an object of the present invention to provide a motor operated butterfly valve arrangement or butterfly valve, the valve element of which can be brought to a proper stop state at an extreme stop position such that no water leak or the like can occur, and without the need to improve the dimensional accuracy or mounting accuracy of individual components, and also without the need to lock the motor.
The object of the invention is achieved by a motor operated butterfly valve arrangement for controlling the opening state of at least one pipe, having at least one valve element movably arranged within the pipe, a motor, and a coupling mechanism between the motor and the valve element in order to vary the orientation of the valve element in relation to the pipe between different opening states with differing orientations of the valve element. At least one of the opening states is defined by mechanical contact between the valve element and a stopper of the pipe. The coupling mechanism includes an elastic coupling member for elastically taking up by deformation an extra driving motion increment of the motor in relation to the valve element as soon as the valve element is stopped at the stopper, the extra driving motion increment continuing the former motor driving motion.
The motor operated butterfly valve has a valve element arranged within a pipe. The valve element has an orientation thereof varied through operation of a motor to control an opening state of the pipe wherein a driving arm rotated by the motor and a driven arm coupled to the valve element are elastically coupled to each other by an elastic coupling member, the motor being controlled to bring the valve element to a stopped state in contact with a stopper at least one extreme stop position thereof. The motor is controlled further on to rotate the driving arm extra after the valve element comes into contact with the stopper and the motor first is stopped after having fulfilled the extra rotation.
According to the present invention in general the motor carries out an extra driving motion increment as soon as said valve element has reached its extreme position, and then the motor is stopped without being locked. In accordance with a further aspect of the invention the driving arm transmitting the driving motion of said motor via said coupling mechanism containing said elastic coupling member is rotated an extra amount by the motor after the valve element has come into contact with the stopper at the predetermined extreme stop position thereof. After said extra rotation, said motor is stopped. The valve element and the driven arm coupled to said valve element remain stopped while the elastic coupling member elastically coupling the driving arm and the driven arm is elastically deformed by the driving force of the motor and the extra rotation thereof, with the result that the elasticity of the coupling member serves to press said valve element firmly against the stopper, and to keep it in a pressed condition. The reaction force of the deformed elastic coupling member can be set weak enough to avoid locking the motor. Accordingly, even if there is a dimensional error, mounting error or the like among the individual components, the valve element can be brought to a proper stop state such that water leakage or the like cannot occur and without the need to lock the motor.
Resulting from the elastic coupling member provided in said coupling mechanism, the coupling mechanism is designed with a restraint lost motion feature, allowing said elastic coupling member to generate a load pressing said valve element into its extreme position by an extra driving motion increment of said motor in continuation of the former driving motion and for a limited extent. Since there is no rigid connection between the motor and the valve element, the motor can be stopped normally after carrying out this extra driving motion increment, without the need to lock it. Said elastic coupling member takes up the extra driving motion increment and generates the desirable pressing force of the valve element. Due to said elastic pressing force, the valve element reaches its extreme position precisely and reliably irrespective of mounting or dimension tolerances, because it is dragged by said elastic coupling member into the correct extreme stopping position. Said extra driving motion increment caused by the motor is of a larger magnitude than needed. This establishes a broad safety margin within which the valve element reliably can be brought into the desired extreme position without the necessity to lock the motor, because the reaction force on the motor can be weak.
In a preferred embodiment, said valve element may have two different extreme positions each defined by a respective stopper. Said elastic coupling member is acting bi-directionally, i.e. generates its lost motion feature in both driving directions of the motor.
Expediently said elastic coupling member is storing the driving power by elastic deformation and is generating an increased contact pressure between the valve element and its stopper. Said contact pressure may be lower than the driving force or driving torque of the motor.
In another embodiment, a single motor is coupled with a plurality of valve elements via a number of elastic coupling members equal to the number of said valve elements. When said motor has carried out its extra driving motion increment after at least one of said valve elements is contacting its respective stopper, all valve elements coupled to said common motor will be reliably brought in their extreme stop positions. Each elastic coupling member then might be deformed different from another depending on the individual tolerance which has been compensated for.
The elastic coupling member may be a spring member engaging with both the driving arm and the driven arm. As soon as the valve element is in contact with the stopper and the driving arm is rotated extra by the motor, the driven arm and the valve element will remain stopped in the correct extreme position while the elastic coupling member is elastically deformed. The magnitude of the extra rotation of said motor has to be set to a value which reliably covers at least the possible tolerances of said valve element and any slacks within the force transmission path between the motor and the valve element.
In an expedient embodiment, the elastic spring member is a coil spring having a forked portion for holding both arms or lateral pins of both arms. As soon as the driving arm is rotated an extra amount by the motor after the valve element contacts the stopper, the elastic spring member is elastically deformed such that a gap defined by said forked portion is widened. Said forked portion design of said spring member is advantageous because said spring member can act in both moving directions of said valve element.
Said extreme stop position of the valve element may be the position at which the pipe is fully closed. Only then said elastic coupling member is deformed to take up the extra driving motion increment of said motor. In the other extreme position of the valve element, which can be the fully opened position, the motor may stop normally without carrying out any extra driving motion.
In an alternative embodiment the pipe may be a branching pipe. The valve element is located at the location of the branch function. The orientation of the valve element can be varied to alternately interconnect two branch pipes of four branch pipes or to interconnect all branch pipes. Two extreme stop positions of said valve elements can be provided where alternatively two respective branch pipes are fully interconnected. In each extreme position, the motor is rotated extra as soon as the valve element has contacted its stopper. It suffices to provide only one elastic coupling member, which is acting bi-directionally.
In another embodiment, there may be a plurality of valve elements in parallel with each other, driven by a common single motor. An elastic coupling member is provided between each of the driven arms of the plurality of valve elements and the motor. There might even be the same number of driving arms as driven arms. If there are deviations among the respective extreme positions of the valve elements because of errors attributable to dimensional accuracy, mounting accuracy, slack in the transmission, etc., the respective elastic coupling element is compensating for said differences automatically when said motor has been rotated an extra amount after at least one of said valve elements has contacted its stopper. The elastic coupling element of each valve element ensures that the orientations of all valve elements may be controlled collectively by the single motor, and that each valve element reliably reaches its extreme position even if the extreme positions slightly differ from one another.
In order to save mounting space and to avoid power losses during the transmission of the driving force of the motor, the output shaft and the valve element shaft ought to be arranged axially with the driving and driven arms essentially parallel to each other, and the elastic spring member coupling both arms via respective lateral pins. The elastic spring member defining said elastic coupling member can be carried either by the valve element shaft or by the motor output shaft, respectively. If the active lever arm of the driven arm is shorter than the active lever arm of the driving arm, said elastic coupling member can even increase the actuation force for the valve element. In order to achieve a predetermined actuating force a low torque motor can be used. In this case, the swivelling stroke of the driving arm is larger than the swivelling stroke of the driven arm. The arrangement can be inversed as well, in order to achieve a relatively enlarged swivelling stroke for the valve element compared to a shorter swivelling stroke or rotation of the motor and the driving arm. In the first mentioned arrangement, the reaction torque of the deformed elastic coupling member is weaker for the motor than the torque keeping the valve element in contact with its stopper.